Patient-specific instrumentation and method for articular joint repair

ABSTRACT

Patient-specific instrumentation for use when performing articular joint repair is provided. A patient-specific jig is adapted to be positioned over a bone at an articular surface thereof for assisting in preparing the bone surface for reception of a prosthesis. The jig comprises a bone contacting portion adapted to matingly contact a portion of the articular surface of the bone and a cutting slot adapted to receive therein a saw blade for resecting the articular surface of the bone. The cutting slot may be press-fitted into the opening of a cut guide. A patient-specific plate and a patient-specific rotational guide are also provided for guiding a positioning of the prosthesis over the resected surface of the bone. A method for manufacturing the patient-specific jig is further provided.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a non-provisional of U.S. provisional Application Ser. No. 61/651,061, filed on May 24, 2012, U.S. Provisional Patent Application No. 61/671,990, filed on Jul. 16, 2012, and U.S. Provisional Patent Application No. 61/787,579, filed on Mar. 15, 2013.

FIELD OF THE APPLICATION

The present application relates to patient-specific instrumentation for articular joint repair.

BACKGROUND OF THE ART

In arthroplasty, a damaged joint, such as a knee joint, is replaced with prosthetic implants. Prior to implantation of the implant, the damaged region of the joint is typically prepared by treating regions of the bones to provide surfaces that can align with and therefore accommodate the implant.

Accuracy in the alignment of the implant is important in the arthroplasty procedure. In knee replacement surgery, this entails proper alignment of the knee so the centre of the hip, knee and ankle are aligned in a straight line. This in turn ensures faster patient rehabilitation and better knee function. For this purpose, mechanical jigs, which ensure accurate position and orientation of finishing instruments used during bone resection, are typically used during arthroplasty procedures, such as knee replacements. However, such conventional jigs may lack precision as they may rely on the user's judgment to assess proper positioning of the devices. In addition, each patient's anatomy being different, proper component sizing may be required for optimizing the outcome of the surgery. Still, conventional components only allow patient customization to a certain degree. As such, the use of conventional instrumentation can lead to misalignment and result in instability and potential wear or even premature failure of the prosthetic implants.

There is therefore a need for improved patient-specific instrumentation for use during articular joint repair procedures.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present invention to provide novel patient-specific instrumentation and method.

Therefore, in accordance with the present application, there is provided a patient-specific rotational guide for guiding a positioning of a tool on a resected surface of a bone in an articular joint repair procedure, the rotational guide comprising a body comprising a tool attachment member adapted to be secured to the tool; and a bone contacting member having a bone contacting surface shaped using patient-specific modeling to conform to a shape of an articular surface of the bone for matingly contacting the articular surface when the tool is positioned on the resected surface.

Further in accordance with the present application, there is provided a patient-specific jig for preparing an articular surface of a bone in an articular joint repair procedure, the patient-specific jig comprising at least one bone contacting member having a mating surface shaped using patient-specific modeling to conform to a shape of the articular surface, the mating surface adapted to matingly contact a portion of the articular surface; and a cutting guide adjacent the at least one bone contacting member and adapted to receive therein a saw blade for resecting the articular surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a flow chart of a method for performing bone resection during arthroplasty using a patient-specific jig in accordance with the present disclosure;

FIG. 1 b is a flow chart of the step of creating a patient-specific jig of FIG. 1 a;

FIG. 2 is a block diagram of a patient-specific instrumentation computer-assisted system for arthroplasty in accordance with the present disclosure;

FIG. 3 is a side perspective view of a patient-specific femoral jig on a femur in accordance with the present disclosure;

FIG. 4 is a bottom perspective view of the patient-specific femoral jig on the femur of FIG. 2;

FIG. 5 is a perspective view of a femur showing femoral jig contacting areas in accordance with the present disclosure;

FIG. 6 is a top perspective view of a tibial jig in accordance with the prior art;

FIG. 7 is a perspective view of the tibial jig of FIG. 5;

FIG. 8 is a top perspective view of a patient-specific tibial jig on a tibia in accordance with the present disclosure;

FIG. 9 is a front perspective view of a tibia showing tibial jig contacting areas in accordance with the present disclosure;

FIG. 10 a is a bottom perspective view of a patient-specific femoral jig on a femur in accordance with an alternative embodiment of the present disclosure;

FIG. 10 b is a side view of the femoral jig of FIG. 10 a;

FIG. 11 a is a rear perspective view of a patient-specific tibial jig on a tibia in accordance with an alternative embodiment of the present disclosure

FIG. 11 b is a top view of the tibial jig of FIG. 11 a;

FIG. 11 c is a top perspective view of the tibial jig of FIG. 11 a;

FIG. 12 is a front perspective view of a patient-specific tibial plate in accordance with the present disclosure;

FIG. 13 a is a perspective view of a rotational guide and of a sizing plate coupled to a plate handle in accordance with a first embodiment of the present disclosure;

FIG. 13 b is a perspective view of the rotational guide of FIG. 13 a coupled to the plate handle and sizing plate;

FIG. 13 c is a side view of the rotational guide of FIG. 13 b;

FIG. 13 d is a perspective view of the rotational guide of FIG. 13 c mated with a bone surface in accordance with a first embodiment of the present disclosure;

FIG. 13 e is a perspective view of a rotational guide and of a sizing plate in accordance with a second embodiment of the present disclosure;

FIG. 13 f is a bottom perspective view of the rotational guide of FIG. 13 e;

FIG. 13 g is a top perspective view of the rotational guide of FIG. 13 e coupled to the sizing plate;

FIG. 13 h is a bottom perspective view of the rotational guide and sizing plate of FIG. 13 g;

FIG. 14 a is a top perspective view of a cut slot in accordance with the present disclosure;

FIG. 14 b is a front view of the cut slot of FIG. 14 a;

FIG. 14 c is a perspective view of the cut slot of FIG. 14 a;

FIG. 14 d is a perspective view of the cut slot of FIG. 14 a inserted into a cut guide in accordance with the present disclosure;

FIG. 14 e is a perspective view of the cut slot of FIG. 14 d showing assembly pins in accordance with the present disclosure;

FIG. 14 f is a perspective view of the cut slot of FIG. 14 e receiving a drop rod adaptor in accordance with the present disclosure; and

FIG. 14 g is a front view of the cut slot of FIG. 14 d with a close-up view of crush ribs in accordance with the present disclosure.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to FIG. 1 a, a method 100 for preparing a bone using patient-specific instrumentation (PSI), and more particularly patient-specific femoral and tibial jigs, prior to performing an arthroplasty procedure, such as knee replacement, will now be described. Although described herein as relating to total knee replacement, it should be understood that the method 100 is also suitable for partial knee replacement, or other articular joint repair procedures known to those skilled in the art. It should also be understood that the method 100 may be suitable for repairing other articular joints, such as an elbow, shoulder, wrist, or hip.

The first step 102 of the method 100 illustratively comprises pre-operative planning, during which image data of the patient's anatomy, e.g. the hip, knee, and ankle regions when total knee replacement is concerned, may be obtained before surgery. The image data may be obtained from scans generated using Magnetic Resonance Imaging (MRI), Computed Tomography (CT), ultrasound, x-ray technology, optical coherence tomography, or the like. Once the images are obtained, a computer software creates a three dimensional (3D) model of the patient's damaged knee joint (step 104), which may be sent to a user over a suitable communication network, such as the Internet. The user may then visualize the 3D model using a computer (not shown) to plan bone resection and prosthesis component placement at the damaged joint region (step 106). The model further enables the user to determine the prosthesis sizing and shape option, e.g. thickness, length, width, or curvature, best adapted to the patient given the latter's age, weight, gender, and other pertinent information.

Referring to FIG. 1 b in addition to FIG. 1 a, once bone resection and prosthesis selection and placement have been planned by the user, the user's computer plan may be used to manufacture patient-specific jigs (step 108). The patient-specific jigs may be manufactured using a jig blank model as a starting point for the machining process (step 112). The jig blank model may be made of any suitable material, including but not limited to a polymer, a metal, a cross-linked polymer, a ceramic, and an alloy. In this case, a jig blank model of a given size, e.g. small, medium, or large, selected from a library of blanks and adapted to the anatomy of the patient's damaged joint may be deconstructed. Parts of the blank model may be removed using a Boolean operation to carve out the desired shape of the patient-specific jigs (step 114). A jig having a surface conforming to the joint surface to which the prosthesis is designed to mate, and thus precisely-fitting the patient's anatomy, may then be obtained (step 116).

A rapid prototyping manufacturing process may further be used to manufacture the patient-specific jigs. In this technique, a computer software may section the 3D representations of an object to be manufactured into a plurality of distinct two-dimensional (2D) layers. A 3D printer then fabricates a layer of material for each layer sectioned by the software. The fabricated layers together form a prototype of the desired object.

During surgery, the thus manufactured jigs may be precisely fitted over the patient's knee bones, namely the femur and tibia, at the damaged region of the knee joint for guiding the bone resection (step 110). In this manner, customized bone preparation may be performed as previously planned on the computer by the user. Optimal placement of the best fitting size and shape of the replacement prosthesis may therefore be achieved.

Referring to FIG. 2, a PSI computer-assisted system for arthroplasty is generally shown at 120. The system 120 illustratively receives at an imagery unit 122 images of the patient's hip, knee, and ankle regions from any appropriate imaging technology, such as MRI or CT. The imaging technology apparatus (not shown) may be part of the system 120. The bone images are then sent to a processor unit 124, which illustratively comprises a bone model generator 126, a planning unit 128, and a PSI generator 130. The processor unit 124 has a processor to run an application that will generate PSI models used to manufacture PSI, such as a PSI tibial jig 132, a PSI femoral jig 134, a PSI plate 136, and a PSI rotational guide 138 for use during the arthroplasty procedure, as will be discussed further below. The processor unit 124 may be any appropriate computer or processing unit. User interfaces, such as a monitor, screen, touch-screen, keyboard, or mouse, may be part of the processor unit 124 for the involvement of an operator in the creation of the PSI models.

The bone model generator 126 is illustratively used to interpret the bone images received from the imagery unit 122 in order to create a 3D model of the patient's damaged articular joint, e.g. the knee joint. For this purpose, input may be provided by an operator via the user interfaces to ensure proper adequate segmentation between bone and tissue as well as bone and cartilage, thus increasing the accuracy of the generated bone model.

The planning unit 128 may then be used to visualize the bone model and to plan bone resection as well as prosthesis component placement at the damaged joint. The prosthesis size and shape best-suited to the patient's unique anatomy may also be determined at the planning unit 128. According to the generated bone model and pre-operative planning, the PSI generator 130 may produce the PSI models, which in turn may be used to manufacture at least one of the PSI tibial jig 132, the PSI femoral jig 134, the PSI plate 136, and the PSI rotational guide 138, the latter being adapted to be placed over a resected bone portion for guiding the position or rotation of a prosthesis component thereon. For this purpose, patient-specific modeling may be used to design PSI tools, e.g. the PSI tibial jig 132, the PSI femoral jig 134, the PSI plate 136, and the PSI rotational guide 138, such that each PSI tool has a mating surface that is a replica of or otherwise precisely conforms to a surface of a bone the tool is to be positioned on. In this manner, the PSI tool matingly contacts the bone surface and precisely fits the patient's anatomy. The PSI models may be in any appropriate format to allow the manufacture of PSI. For instance, the PSI models may be formatted into numerical control (NC) machine files, technical data, visual or digital models, etc.

Referring now to FIG. 3 and FIG. 4, a femoral jig 200 may first be used to prepare a distal femoral surface prior to attaching a prosthesis component thereon, in most cases with a bone cement. The femoral jig 200 illustratively comprises a bone contacting portion 202 adapted to be positioned on the patient's femur 204 in flush contact with an articular surface 206 thereof.

The femoral jig 200 illustratively comprises a cut-slot portion 208 having a cutting slot 210 formed therein and adapted to receive a saw blade (not shown) used to execute the pre-planned bone cuts. When the femoral jig 200 is in position over the femur 204 following exposure of a distal end thereof during surgery, the cut-slot portion 208 illustratively extends along the anterior-posterior direction A. In this manner, when the femoral jig 200 is in place, the slot 210 is positioned adjacent to the trochlear groove 212 at a lower portion of the femur 204, which typically mates with an upper portion of the patient's tibia (not shown) at the knee joint. The saw blade may therefore be used to resect the lower portion of the femur 204.

The bone contacting portion 202 of the femoral jig 200 further comprises a first pair of pegs 214 a and 214 b, which are respectively positioned adjacent to the medial and lateral femoral condyles 216 a and 216 b and extend away from the femur 204 along the cranial-caudal direction B when the femoral jig 200 is in place. The pegs 214 a and 214 b each have elongated guide bores 218 a and 218 b running therethrough and adapted to receive therein the drill bit of a surgical drill (not shown). In this manner, the user may drill elongated holes (not shown) into the femur 204. The thus machined holes are adapted to receive therein fixations, such as pins, screws, or the like, to couple the femoral jig 200 to the femur 204 prior to resection thereof. Proper alignment of the pegs 214 a and 214 b along the medio-lateral direction C may further be verified using a device, such as a cut guide 220. For this purpose, the cut guide 220 may be positioned adjacent the pegs 214 a and 214 b and proper alignment with features, as in 222 a, 222 b provided on the cut guide 220, may be verified. In particular, the bores 218 a and 218 b may be used as guides to drill holes in the distal end of the femur 204 for positioning the cut guide 220 in a pre-planned position. Any cuts required to position the prosthesis component in the preplanned position may be subsequently performed.

The bone contacting portion 202 of the femoral jig 200 further illustratively comprises a second pair of pegs 224 a and 224 b, which are positioned adjacent the cut-slot portion 208 and extend away from the femur 204 along the anterior-posterior direction A when the femoral jig 200 is in place. The pegs 224 a and 224 b each have elongated guide bores (not shown) running therethrough and adapted to receive therein fixations, such as pins, screws, or the like, to further securely attach the femoral jig 200 to the femur 204 prior to resection thereof. Fixations are illustratively first inserted into the pegs 224 a and 224 b for attaching the femoral jig 200 to the femur 204, followed by insertion of fixations into the pegs 214 a and 214 b for further stabilizing the femoral jig 200 in place.

Once the femoral jig 200 has been secured and stabilized, the fixations inserted into the pegs 214 a and 214 b may be removed to enable resection of the distal end of the femur 204. After the femur 204 has been resected, fixations may be inserted back into the pegs 214 a and 214 b for attaching a standard cutting block (not shown) to the resected bone. In this manner, additional cuts, e.g. remaining ones of the five femoral cuts to be performed during total knee arthroplasty, may be effected on the femur 204.

As can be seen from FIG. 3 and FIG. 5, the use of the femoral jig 200 advantageously enables the user to have an improved lateral view of the femur 204, in addition to having a clear view of the trochlear groove 212. Indeed, a distal clearance (reference 211 a in FIG. 4) is illustratively formed in the bone contacting portion 202 in the area between the cut-slot portion 208 and the pegs 214 a and 214 b. The clearance 211 a may be shaped and sized to conform to a shape and size of the trochlear groove 212. A lower surface 213 of the bone contacting portion 202 may also be shaped so as to contact a reduced surface of the femur 204. In particular, the shape of the lower surface 213 illustratively defines a medial clearance 211 b and a lateral clearance (not shown). The medial clearance 211 b and the lateral clearance provide viewing spaces that enable a user to evaluate the degree of contact between the femoral jig 200 and the distal surface of the medial and lateral femoral condyles 216 a and 216 b. The distal clearance 211 a similarly enables to evaluate contact over the surface on the anterior part (not shown) of the condyles 216 a and 216 b. As seen in FIG. 5, when the femoral jig 200 is in position, the bone contacting portion 202 illustratively makes contact with the femur 204 at a medial femoral condyle contact area 226 a, a lateral femoral condyle contact area 226 b, and an anterior surface contact area 228. The femoral condyle contact areas 226 a and 226 b are illustratively positioned on the distal part of the medial and lateral femoral condyles 216 a and 216 b, respectively, while the anterior surface contact area 228 is positioned on the anterior part of the condyles 216 a and 216 b. In one embodiment, the anterior surface contact area 228 is defined by tabs (not shown) provided on the femoral jig 200 and extending over the flank of the lateral femoral condyle 216 b and over the medial side (not shown) of the femur 204 accessible during the surgical procedure. The contact areas 226 a, 226 b, and 228 are illustratively sized so as to be proportional to the size of the femur 204. Visibility of the trochlear groove 212 further ensures that the femoral jig 200 is properly positioned on the femur 204.

The areas of contact between the femoral jig 200 and the femur 204 may vary from one patient to the next and are illustratively proportional to bone size. Still, the femoral jig 200 is illustratively designed such that, when the femoral jig 200 is in place, no contact is made with areas of the femur 204 where cartilage or soft tissues and osteophyte formation resulting from osteoarthritis may be present. For instance, in the embodiment illustrated in FIG. 5, the contact areas 226 a and 226 b are located on the articular surface of the femur 204 and avoid the medial and lateral margins (not shown) where osteophytes may be present. This in turn optimizes the precision of the arthroplasty procedure and improves an outcome thereof. Indeed, it is desirable for the femoral jig 200 to make contact with as few areas of the exposed femur 204 as possible so as to reduce the inaccuracies in the surgical cuts to be effected.

Referring now to FIG. 6 and FIG. 7, a prior art tibial jig 300 will now be described. The tibial jig 300 is adapted to be precisely fit on an articular surface 302 of the patient's tibia 304. The tibial jig 300 illustratively comprises a tibia contacting portion 306 and a pair of attachment arms 308 a and 308 b each having respectively formed at an end portion thereof plateau contacting portions 310 a and 310 b. When the tibial jig 300 is placed over the tibia 304 following exposure of a proximal end thereof, the tibia contacting portion 306 is adapted to contact the tibia 304. The attachment arms 308 a and 308 b then extend away from the tibia 304 along the anterior-posterior direction A with the plateau contacting portion 310 a making contact with the articular surface of the medial tibial plateau 312 a and the plateau contacting portion 310 b making contact with the articular surface of the lateral tibial plateau 312 b.

The tibial jig 300 further comprises a cut-slot portion 314 having a slot 316 adapted to receive therein a saw blade 318 used by the user to execute the pre-planned bone cuts. When the tibial jig 300 is in place on the tibia 304, the cut-slot portion 314 is positioned adjacent an upper portion of the tibia 304, which typically mates with a lower portion of the femur 204 at the knee joint. In this position, the slot 316 extends along the transverse plane and the saw blade 318 may be inserted through the slot 316 to resect the upper portion of the tibia 304. The resected surface of the tibia 304 is in most cases perpendicular to the shaft axis Y of the tibia 304 in the coronal plane. The slot 316 may further be machined into the cut-slot portion 314 so as to enable proper reach of the saw blade 318 during the bone resection.

The pair of attachment arms 308 a and 308 b may respectively comprise pegs 320 a and 320 b, which extend away from the tibia 304 along the cranial-caudal direction B. The pegs 320 a and 320 b each have elongated guide bores 322 a and 322 b running therethrough and adapted to receive therein a surgical drill bit (not shown) used to drill elongated holes into the tibia 304. The thus machined holes are then mated with holes provided in a provisional tibial sizing plate 324 used to determine the proper size of a prosthetic tibial tray (not shown). The holes in the sizing plate 324 are adapted to receive therein fixations, such as pins, screws, or the like, to securely attach the sizing plate 324 to the resected portion of the tibia 304. For this purpose, the elongated guide bores 322 a and 322 b are spaced and sized to match the spacing and size of bores 326 a and 326 b machined into the sizing plate 324. The bores 322 a and 322 b thus aid in setting the position and rotation of the sizing plate 324 on the resected portion of the tibia 304. With the proper sizing plate 324 selected and held in place, the proximal tibia can be further drilled and/or broached to accommodate supporting components, such as stems, of the prosthetic tibial tray.

A second pair of pegs 328 a and 328 b illustratively project from the tibia contacting portion 306 and extend away from the tibia 304 along the anterior-posterior direction A when the tibial jig 300 is in place. The pegs 328 a and 328 b each have elongated guide bores (not shown) running therethrough and adapted to receive therein a device, such as a drop rod (not shown), for confirming, subsequent to the tibial cut, that proper rotation and alignment of the cut relative to the overall tibial shaft axis Y have been achieved using devices, such as traditional tibial component sizing jigs and rotational jigs.

Referring to FIG. 8 and FIG. 9, a tibial jig 400 in accordance with an illustrative embodiment will now be described. The tibial jig 400 illustratively comprises a pair of attachment arms 402 a and 402 b each having a surface contacting portion (not shown) so that the arms 402 a, 402 b may respectively make contact with the articular surfaces 404 a and 404 b of the medial tibial plateau 312 a and of the lateral tibial plateau 312 b. The slope of the tibial intercondylar eminence 405 may further be used to lock the medio-lateral position as well as the rotation of the tibial jig 400. In particular, when the tibial jig 400 is in place, the attachment arms 402 a and 402 b may contact the sides of the intercondular eminence 405, thereby providing stability to the tibial jig 400.

The tibial jig 400 further comprises a cut-slot portion 406 having a slot 408 adapted to receive therein a saw blade (not shown) used to perform resection of the tibia 304. A tibia contacting portion (not shown) is further provided adjacent the cut-slot portion 406 for making contact with the tibia 304 on a region 410 of the medial and lateral tibial plateaus 312 a and 312 b adjacent the tibial tuberosity 411. When the tibial jig 400 is in position on the tibia 304, the cut-slot portion 406 is illustratively adjacent an upper portion of the tibia 304 with the slot 400 being parallel to the transverse plane. At least one line indicator 412 may further be provided on the cut-slot portion 406 adjacent the attachment arm 402 a. The line indicator 412 may be locate on the jig 400 using patient-specific modeling. Alignment of the indicator 412 with the tibial tuberosity 411 may be used to confirm that the tibial jig 400 is positioned at a desired rotational angle relative to the tibia 304. In one embodiment, a first and second indicator as in 412 may be respectively provided on the anterior and distal sides cut-slot portion 406 to indicate alignment with the anterior-posterior direction A. A cut slot plane indicator (not shown) may also be provided on the medial side of the cut-slot portion 406 to indicate alignment with the plane along which the pre-planned bone cuts are to be performed.

Although the areas of contact between the tibial jig 400 and the tibia 304 may vary from one patient to the next, a lower surface (not shown) of the attachment arms 402 a and 402 b is illustratively sized and/or shaped such that no mating of the tibial jig 400 is made on an area 413 of the tibia 304 where meniscus may be present, thus avoiding any soft tissues remaining on the tibia 304 following exposure thereof. For instance, the arms 402 a, 402 b may be provided with varus-valgus shapes. Also, the tibia contacting portion is illustratively sized and/or shaped so as to avoid possible osteophytes that may be present on the anterior proximal ridge (not shown) of the tibia 304.

The tibia contacting portion illustratively has formed therein a pair of pegs 414 a and 414 b, which project away from the tibia contacting portion along the anterior-posterior direction A when the tibial jig 400 is in place. Elongated guide bores (not shown) may be machined into the pegs 414 a and 414 b for receiving fixations used to secure the tibial jig 400 to the tibia 304. If, subsequent to resection of the tibia 304 using the saw blade, it is determined that an insufficient amount of bone has been resected, a standard cutting block (not shown) may be secured to the pegs 414 a and 414 b for performing additional bone cuts. A clearance (not shown) having a shape and size conforming to the shape and size of the area 413 may further be formed in the tibia contacting portion to ensure that no contact is made with the area 413 of the tibia 304.

FIGS. 10 a to 10 b and FIGS. 11 a to 11 c illustrate alternate embodiments of the femoral jig 200 and of the tibial jig 400. FIG. 10 a and FIG. 10 b illustrate an alternate embodiment 500 of the femoral jig 200 shown in FIGS. 3 and 4. In this embodiment, the femoral jig 500 comprises a bone contacting portion 502 adapted to be positioned on the patient's femur 204 in flush contact with an articular surface 206 thereof, as produced by patient-specific fabrication. The bone contacting portion 502 further comprises a first pair of pegs 504 a and 504 b, which are respectively positioned adjacent to the medial and lateral femoral condyles (not shown) and extend away from the femur 204 along the cranial-caudal direction (reference B in FIG. 3) when the femoral jig 500 is in place. The pegs 504 a and 504 b each have elongated guide bores (not shown) running therethrough and adapted to receive therein the drill bit of a surgical drill (not shown).

The bone contacting portion 502 also comprises a second pair of pegs 506 a and 506 b, which extend away from the femur 204 along the anterior-posterior direction (reference A in FIG. 3) when the femoral jig 500 is in place. The pegs 506 a and 506 b each have elongated guide bores (not shown) running therethrough and adapted to receive therein fixations, such as pins, screws, or the like, to further securely attach the femoral jig 500 to the femur 204 prior to resection thereof.

A clearance 508 may be formed in the bone contacting portion 502 in an area between the pegs 506 a and 506 b and the pegs 504 a and 504 b. A lower surface 510 of the bone contacting portion 502 may also be shaped so as to contact a reduced surface of the femur 204.

The femoral jig 500 further comprises a line indicator 511 used to indicate the desired location of the bone cut to be performed on the femur 204. The femoral jig 500 may further comprise a mechanical axis pointer 512 provided in between the pegs 504 a and 504 b. The pointer 512 illustratively provides an indication as to whether the femoral jig 500 is properly positioned on the femur 204. In particular, proper positioning is achieved if the pointer 512 points towards the femur's mechanical axis (not shown), as defined during the pre-operative planning phase. A pair of transepicondylar line indicators 514 a and 514 b may further be provided on the bone contacting portion 502 adjacent the pegs 504 a and 504 b, respectively. The indicators 514 a and 514 b illustratively protrude away from the bone contacting portion 502 to align with the lateral and medial epicondyles (not shown).

FIG. 11 a and FIG. 11 b illustrate an alternate embodiment 600 of the tibial jig 400 shown in FIG. 8. In this embodiment, the tibial jig 600 comprises a pair of attachment arms 602 a and 602 b each having a surface contacting portion (not shown) so that the arms 602 a, 602 b may respectively make contact with the articular surfaces (not shown) of the medial tibial plateau 312 a and of the lateral tibial plateau 312 b. A tibia contacting portion 604 is positioned adjacent an upper portion of the tibia 304 and comprises elongated guide bores 606 a and 606 b adapted to receive fixations for securing the tibial jig 600 to the tibia 304. A line indicator 608 may further be provided on the tibial jig 600 adjacent the tibia contacting portion 604. Proper positioning of the tibial jig 600 relative to the tibia 304 may be confirmed by alignment of the indicator 608 with the tibial tuberosity (not shown). Patient-specific modeling may be used to determine the position of the indicators 511, 514 a, 514 b, and the pointer 512 on the femoral jig 500 as well as the position of the indicator 608 on the tibial jig 600.

Use of the femoral jigs 200, 500 and the tibial jigs 400, 600 advantageously decreases errors and enables more precise prosthesis placement compared to traditional mechanical jigs. In addition, fewer instruments need to be sterilized for use during the surgical procedure. For instance, the use of patient-specific jigs as in 200, 400, 500, or 600 precludes the need for inserting rods through the intramedullary canal of the bone during the arthroplasty procedure. This in turn reduces the risk of perioperative fat embolism syndrome. Moreover, the use of patient-specific jigs as in 200, 400, 500, or 600 further allows for smaller incisions to be made in the patient's body, thus facilitating completion of minimally invasive surgery and allowing the prosthesis to more quickly restore the patient's joint to a generally pre-deteriorated state.

Referring now to FIG. 12, a patient-specific plate 700 may be placed over the resected portion of the tibia 304 for guiding the position and/or rotation of the sizing plate as in 324 over the resected bone area. For this purpose, a contour 702 of the plate 700 may be designed so as to closely follow a contour of the tibial cut. Apertures as in 704 a and 704 b may further be machined into the plate 700 for guiding the user as to where in the tibia 304 holes should be drilled so as to receive fixations of the sizing plate 324, thereby attaching the latter to the tibia 304.

In order to ensure a proper fit of the tibial tray (not shown) on the resected portion of the tibia 304, and accordingly a proper positioning of the prosthesis, an outline or contour 706 of the tibial tray may be etched or otherwise delineated onto an upper surface 708 of the plate 700. Such a contour 706 may be obtained as a result of the user's pre-operative planning, during which the size and shape of the prosthesis best-suited to the patient's anatomy has been selected. In addition, a first axis 710 substantially parallel to the anterior-posterior direction A and a second axis 712 substantially parallel to the medio-lateral direction C may be machined on the surface 708 of the plate 700. In this manner, while placing the tibial tray on the resected portion of the tibia 304, a user may verify a proper alignment thereof relative to the axes 710 and 712, thereby ensuring proper positioning of the prosthesis. It should be understood that additional alignment features as well as other indications, such as the size and model of the prosthesis component, may also be shown on the surface 708.

Referring to FIGS. 13 a to 13 d, a patient-specific rotational guide 800 may be used as an alternative to the patient-specific plate 700 to ensure proper positioning and rotation of the sizing plate 324 on the resected portion of the tibia (not shown). The rotational guide 800 illustratively comprises a tray attachment member 802 for coupling the rotational guide 800 to the sizing plate 324. The rotational guide 800 may further comprise a bone contacting member 804 for contacting a bone the sizing plate 324 is to be mated with, the bone contacting member 804 being produced by patient-specific fabrication using bone imaging. Although a tibial sizing plate 324 has been shown for illustrative purposes, it should be understood that the rotational guide 800 may be adapted for use on a bone other than the tibia, for example on the distal portion of a femur (not shown). It should also be understood that the rotational guide 800 may be used with a variety of jig types as well as for repair of various articular joints other than the knee.

The tray attachment member 802 may be coupled to the sizing plate 324 using suitable attachment means (not shown). For instance, the tray attachment member 802 may be clipped to a plate handle 806 coupled to the sizing plate 324. It should be understood that other means of securing the tray attachment member 802 of the rotational guide 800 to the sizing plate 324 may apply.

As shown in FIG. 13 c and FIG. 13 d, the bone contacting member 804 may comprise a PSI bone contacting surface 808 adapted to mate with a corresponding bone surface 810 of the bone the sizing plate 324 is to be positioned on. The bone contacting member 804 is designed so that the bone contacting surface 808 precisely matches a geometry of the bone surface 810. For this purpose, the bone contacting member 804, and more particularly the bone contacting surface 808, may be manufactured from image data of the patient's anatomy obtained during pre-operative planning, as discussed above. In this manner, accurate positioning of the sizing plate 324 relative to the bone surface 810 may be achieved.

Referring to FIGS. 13 e to 13 h, a patient-specific rotational guide 812 in accordance with another embodiment will now be described. The rotational guide 812 comprises a tool attachment member 814 configured to secure the rotational guide 812 to a tool, such as the bone sizing plate 324. The rotational guide 812 further comprises a bone attachment member 816 having a mating surface (not shown) configured to contact a bone (not shown) the tool is mated with. The mating surface is illustratively shaped so as to conform to a shape of the bone surface the bone attachment member 816 is mated with.

In one embodiment, the tool attachment member 814 has a contour (not shown) conforming to the perimeter (not shown) of the tool. The tool attachment member 814 further has a lower surface 818 adapted to mate with the tool. For this purpose, an inner contour 820 of the lower surface 818 is configured so as to conform to a shape of the tool. In this manner, the rotational guide 812 can be retained in position relative to the tool when the rotational guide 812 is secured thereto. The lower surface 818 is further provided with attachment means 822, such as clipping means, that enable attachment of the rotational guide 812 to the tool. In one embodiment, the attachment means 822 comprise a first and a second clipping means that allow the rotational guide 812 to be clipped to the tool. It should be understood that any other suitable attachment means may be provided.

An upper surface 824 of the rotational guide 812 is illustratively provided with one or more alignment elements as in 826 a, 826 b, 826 c, 826 d, and 826 e used for confirming the pre-operative planning intra-operatively. The alignment elements as in 826 a, 826 b, 826 c, 826 d, and 826 e may further be used for guiding the positioning of the tool on the resected bone surface. In particular, the alignment element 826 a may be an anterior-posterior line formed on the upper surface 824 and indicative of an anterior-posterior direction of the bone. The alignment element 826 b may be an medio-lateral line formed on the upper surface 824 and indicative of a medio-lateral direction of the bone. The alignment element 826 c may be indicative of a direction of the mechanical axis of the bone. It should be understood that other anatomical directions may apply. The alignment elements as in 826 d may comprise openings adapted to cooperate with apertures as in 828 formed in the tool, e.g. the bone sizing plate 324. In particular, when the rotational guide 812 is coupled to the plate 324, the alignment elements 826 d may be aligned with the apertures 828 to enable fixations (not shown) to be received in the apertures 828 for securing the plate 324 on the resected surface. The alignment elements 826e may comprise cutouts formed in the tool attachment member 814 and adapted to cooperate with apertures as in 830 of the tool, e.g. the bone sizing plate 324. When rotational guide 812 is coupled to the plate 324, the alignment elements 826 e may also be aligned with the apertures 830 to enable fixations, such as a screws or the like, to be received in the apertures 830.

FIG. 14 a, FIG. 14 b, and FIG. 14 c show and illustrative embodiment of a cut slot 900 for use with at least one of the above-mentioned tibial and femoral jigs. It should be understood that the tibial and femoral jigs may or may not comprise such a cut slot 900 and that the cut slot 900 may be used with non PSI tools. In addition, the cut slot 900 may be provided as a disposable tool for use with disposable instruments, such as disposable cut guides.

The cut slot 900 illustratively comprises a first member 902 and a second member 904 each comprising opposite ends as in 906 ₁, 906 ₂. Each one of the members, e.g. member 902, is provided at the ends thereof, e.g. ends 906 ₁, with an attachment means, e.g. attachment means 908 ₁, adapted to cooperate with the corresponding attachment means, e.g. attachment means 908 ₂, provided at the ends, e.g. ends 906 ₂, of the other member, e.g. member 904. When so coupled to one another, the first and second members 902, 904 define therebetween a spacing 910 adapted to receive therein a saw blade (not shown) used to execute pre-planned bone cuts. In the illustrated embodiment, the attachments means 908 ₁, 908 ₂ are adapted to be snap-fitted together. It should be understood that other attachment means configurations may also apply. It should also be understood that the attachment means 908 ₁, 908 ₂ may be provided at a single one of the ends 906 ₁, 906 ₂ of each member 902, 904 rather than at both ends 906 ₁, 906 ₂thereof.

The cut slot 900 is illustratively metallic and the members 902, 904 may be made of a stamped sheet of metal. It should be understood that a variety of manufacturing processes may be used for the cut slot 900. For example, the members 902, 904 may be machined, formed, or the like. Still, regardless of the manufacturing process used, it is desirable for the cut slot 900 to have a substantially constant width along a length thereof.

Referring now to FIG. 14 d, FIG. 14 e, and FIG. 14 f, the cut slot 900 may be inserted into a housing 912, such as a cut guide housing. The housing 912 may be made of plastic or any other suitable material. The cut slot 900 may be press-fitted into an elongate opening 913 machined into the housing 912. For this purpose, the first and second members (references 902, 904 of FIG. 14 a) may be shaped to fit the size of the opening 913. A lip 914 may further be formed in each one of the first and second members 902, 904 so as to guide, and accordingly facilitate, the insertion of the saw blade into the spacing (reference 910 in FIG. 14 b). Assembly pins 915 may then be used to retain the cut slot 900 within the housing 912. The housing 912 may further comprise a plurality of apertures as in 916 for receiving therein bushings 917 (see FIG. 14 f) as well as a receptor 918 for a drop rod adaptor 919 (see FIG. 14 f). In one embodiment, the bushings 917 are press-fitted into plastic. The bushings may be adapted to accommodate the drill bit of the surgical drill guide (not shown) and may be used to prevent residual plastic shavings or other debris resulting from the drilling process. The bushings 917 may also be used to secure the cut slot 900 on the bone during cutting. In particular, a locking bushing (not shown) may be provided to stabilize the cut slot 900, and accordingly the tibial or femoral jig the cut slot 900 is coupled to, during the cutting procedure. Accurate positioning of the cut slot 900 relative to the bone may then be achieved.

As seen in FIG. 14 f, the drop rod adaptor 919 may be aligned with two anterior medial bushings 917 for accurately positioning the drop rod adaptor 919 in varus-valgus as well as ensuring proper rotation of the drop rod adaptor 919 relative to the cut slot 900. The drop rod adaptor 919 may be further stabilized by a ball plunger (not shown) provided thereon. When the drop rod adaptor 919 is inserted into the receptor 918, the ball plunger may indeed be retained within an aperture (not shown) formed in the receptor 918. The drop rod 919 may further be provided with apertures adapted to cooperate with the bushings 917 for receiving pins as in 921. Pinning can then be performed while the drop adaptor 919 is in place relative to the cut slot 900.

Referring to FIG. 14 g, in order to provide accuracy and stability to the positioning of the cut slot 900 relative to the housing 912, the latter illustratively has formed therein a pair of inferior crush ribs 920 a and a pair of lateral crush ribs 920 b. It should be understood that any other suitable number of crush ribs 920 a, 920 b may be used. The crush ribs 920 a and 920 b ensure that the cut slot 900 is stable as well as account for tolerance variations between the metallic cut slot 900 and the plastic housing 912.

The inferior crush ribs 920 a are illustratively positioned adjacent a lower surface (not shown) of the second member 904. The lateral crush ribs 920 b are respectively positioned adjacent the edge (reference 906 ₁ in FIG. 14 a) of the first member 902 and the edge (reference 906 ₂ in FIG. 14 b) of the second member 902. Other suitable configurations may apply. The crush ribs 920 a and 920 b may be made of resilient or other suitable material, such as plastic, so as to allow the cut slot 900 to be press-fitted within the housing 912. In particular, each crush rib 920 a or 920 b illustratively comprises a base portion (not shown) secured to the housing 912 and a deformable portion (not shown) extending away from the base portion and into the opening (reference 913 in FIG. 14 d) formed in the housing 912. When the cut slot 900 is inserted into the opening 913, the cut slot 900 comes into contact with the deformable portion of the crush ribs 920 a and 920 b. The deformable portion is then crushed, bent, or otherwise deformed or deflected as a result of the pressure exerted thereon by the cut slot 900 during insertion. As a result, the cut slot 900 is then securely retained within the opening 913.

The embodiments of the invention described above are intended to be exemplary. Those skilled in the art will therefore appreciate that the foregoing description is illustrative only, and that various alternate configurations and modifications can be devised without departing from the spirit of the present invention. Accordingly, the present invention is intended to embrace all such alternate configurations, modifications and variances which fall within the scope of the appended claims. 

1. A patient-specific rotational guide for guiding a positioning of a tool on a resected surface of a bone in an articular joint repair procedure, the rotational guide comprising: a body comprising: a tool attachment member adapted to be secured to the tool; and a bone contacting member having a bone contacting surface shaped using patient-specific modeling to conform to a shape of an articular surface of the bone for matingly contacting the articular surface when the tool is positioned on the resected surface.
 2. The patient-specific rotational guide of claim 1, wherein the tool attachment member has an inner contour conforming to a shape of the tool for retaining the tool attachment member in position relative to the tool when the tool attachment member is secured to the tool.
 3. The patient-specific rotational guide of claim 1, wherein the tool attachment member has an outer contour conforming to a perimeter of the tool.
 4. The patient-specific rotational guide of claim 1, wherein the tool attachment member comprises at least one attachment means securing the tool attachment member to the tool.
 5. The patient-specific rotational guide of claim 1, wherein the body comprises at least one alignment element located on the body using patient-specific modeling for guiding the positioning of the tool on the resected surface of the bone.
 6. The patient-specific rotational guide of claim 5, wherein the at least one alignment element is indicative of at least one anatomic direction of the bone.
 7. The patient-specific rotational guide of claim 6, wherein the at least one alignment element is indicative of at least one of a mechanical axis, a medio-lateral direction, and an anterior-posterior direction of the bone.
 8. The patient-specific rotational guide of claim 5, wherein the tool has formed therein at least one aperture and the at least one alignment element comprises at least one opening adapted to cooperate with the at least one aperture when the tool attachment member is secured to the tool, the cooperating at least one aperture and at least one opening adapted to receive therein at least one fixation for securing the tool to the resected surface.
 9. A patient-specific jig for preparing an articular surface of a bone in an articular joint repair procedure, the patient-specific jig comprising: at least one bone contacting member having a mating surface shaped using patient-specific modeling to conform to a shape of the articular surface, the mating surface adapted to matingly contact a portion of the articular surface; and a cutting guide adjacent the at least one bone contacting member and adapted to receive therein a saw blade for resecting the articular surface.
 10. The patient-specific jig of claim 9, wherein the at least one bone contacting member has formed therein at least one clearance shaped to conform to a shape of at least one selected area of the articular surface for preventing contact between the mating surface and the at least one selected area.
 11. The patient-specific jig of claim 10, wherein the at least one clearance is shaped to prevent contact between the mating surface and at least one of cartilage, soft tissue, osteophytes, and menisci.
 12. The patient-specific jig of claim 11, wherein the mating surface of the at least one bone contacting member is adapted to matingly contact a distal surface of a lateral femoral condyle, a distal surface of a medial femoral condyle, an anterior surface of the lateral femoral condyle, and an anterior surface of the medial femoral condyle.
 13. The patient-specific jig of claim 11, wherein the mating surface of the at least one bone contacting member is adapted to matingly contact a proximal surface of a lateral tibial plateau, a proximal surface of a medial tibial plateau, and an anterior proximal tibial surface.
 14. The patient-specific jig of claim 13, wherein the mating surface of the at least one bone contacting member is shaped to conform to a shape of a tibial intercondylar eminence for securing a medio-lateral position and a rotation of the jig relative to the bone when the mating surface matingly contacts the articular surface.
 15. The patient-specific jig of claim 11, wherein the mating surface of the at least one bone contacting member has a first size proportional to a second size of the bone.
 16. The patient-specific jig of claim 9, wherein the at least one bone contacting member comprises at least one alignment element defined on the at least one bone contacting member using patient-specific modeling for guiding a positioning of the jig on the resected surface of the bone.
 17. The patient-specific jig of claim 16, wherein the at least one alignment element is indicative of at least one anatomical direction of the bone.
 18. The patient-specific jig of claim 17, wherein the at least one alignment element is indicative of at least one of an anterior-posterior direction of the bone and a mechanical axis of the bone.
 19. The patient-specific jig of claim 16, wherein the at least one alignment element is indicative of a plane along which the articular surface is to be resected.
 20. The patient-specific jig of claim 9, wherein the cutting guide comprises an opening for receiving therein an insert, the insert comprising a first member and a second member coupled to the first member and spaced therefrom for defining an aperture adapted to receive therein the saw blade. 